Nuclear fission reactors using fissile fuels in the form of molten halide salts have many advantages over solid fuelled reactors but generally suffer from problems due to continuous changes in the chemical composition of the molten fuel salt during operation as fission products accumulate and a net release of halogen from the actinide tri or tetrahalide fuel occurs. Most designs of molten salt reactors incorporate a continuous chemical treatment process in the fuel circulation to manage this problem, however doing so involves adding complex chemical engineering systems into a highly radioactive environment.
A much simpler design of molten salt reactor was described in GB 2508537 in which the fuel salt was held in static tubes in which convection or other mixing processes allowed heat to pass from the fuel salt to the tube wall at a sufficient rate for the reactor to have a practical energy production. Such static fuel tubes do not permit continuous active adjustment of the chemistry of the fuel salt. In GB 2508537 it was suggested that inclusion of metals such as niobium, titanium or nickel in the fuel salt or on the fuel tube would be useful in scavenging excess halogen released during fission but no specific suggestions were made for controlling deleterious effects of fission products.